﻿using Microsoft.AspNetCore.Mvc.Routing;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System.Security.Cryptography;
using System.Text;
using System.Text.Encodings.Web;
using System.Web;

namespace XxSystem.FileManager.core
{
    public class CryptUtil
    {
        public static byte[] keys;
        public static byte[] IV;
        static CryptUtil()
        {
            using (Aes myAes = Aes.Create())
            {
                keys = myAes.Key;
                IV = myAes.IV;
            }
        }
        public static string AesEncrypt(string original)
        {

            // Create a new instance of the Aes
            // class.  This generates a new key and initialization
            // vector (IV).

            // Encrypt the string to an array of bytes.
            byte[] encrypted = EncryptStringToBytes_Aes(original, keys, IV);
            var rs = WebEncoders.Base64UrlEncode(encrypted);
            return rs;

        }
        public static string AesDecrypt(string str)
        {
            // Create a new instance of the Aes
            // class.  This generates a new key and initialization
            // vector (IV).            
            //var s = HttpUtility.UrlDecode(str);
            byte[] toEncryptArray = WebEncoders.Base64UrlDecode(str);

            // Decrypt the bytes to a string.
            string roundtrip = DecryptStringFromBytes_Aes(toEncryptArray, keys, IV);
            return roundtrip;
        }
        static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");
            byte[] encrypted;

            // Create an Aes object
            // with the specified key and IV.
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create an encryptor to perform the stream transform.
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                        encrypted = msEncrypt.ToArray();
                    }
                }
            }

            // Return the encrypted bytes from the memory stream.
            return encrypted;
        }

        static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");

            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;

            // Create an Aes object
            // with the specified key and IV.
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create a decryptor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for decryption.
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }
            }

            return plaintext;
        }
    }
}
